Lock



l9; i POLK] LOCK Filed May 22, 1936 INVENTOR. JAL/VIA R POLK ATTORNEYS Patented Apr. 19, 1938 UNITED STATES PATENT orrice Application May 22,

7 Claims.

This invention relates to looks and more particularly to key-operated locks.

One of the objects of the invention is to provide a key operated lock which cannot be unlocked with any key other than the one designed for it.

Another object of the invention is to provide a lock which practically cannot be picked with a wire or like implement.

Another object is to provide a lock having a plurality of tumblers in which the first tumbler blocks the keyhole when it is in its unlocked position, thereby preventing access to the other tumblers.

The above and other objects of the invention may be attained by providing a body portion having a bifurcated tumbler slidably mounted therein with its legs straddling a keyhole in the body portion. The legs are provided with overlapping ridges which normally lie out of register with the keyhole but which are in register there with when the tumbler is withdrawn into the body portion, thereby preventing insertion of a straight instrument into the'keyhole. A key-is provided having a plurality of cam slots adapted to engage the ridges to cam the tumbler into the body portion, thereby unlocking the lock. If desired, a plurality of such tumblers: may be provided, or tumblers of another type may be arranged back of the first tumbler, thereby making it more difiicult if not impossible to unlock the lock with anything other than the intended key. Preferably the tumbler or tumblers are retained in their locked position, i. e. the position extending outwardly from the body by means of springpressed latches which are released by insertion of the key in the keyhole.

Other objects, advantages and novel features of the invention will be apparent from the following description when read in connection with the accompanying drawing, in which:

igure 1 is a central section of a lock embodying the invention;

Figure 2 is an enlarged partial section on the line 22 of Figure 1;

Figures 3 and 4 are views of the opposite legs of the first tumbler of Figure 1;

Figures 5 and 6 are side elevations of Figures 3 and 4 respectively;

Figures 7 and 8 are elevations showing opposite sides of a key for use with the lock of Figure 1;

Figure 9 is a view similar to Figure 1 of a modified form of lock;

Figures 10 and 11 are elevations of opposite 1936, Serial No. 81,148

sides of a key for use with the lock of Figure 9;

Figures 12 and 13 are views of opposite legs of one of the tumblers of Figure 9;

Figures 14 and 15 are similar views of the other tumbler;

Figure 16 is a central section of a further modified construction;

Figure 17 is a side elevation of the lock of Figure 16;

Figure 18 is an end view of Figure 16;

Figure 19 is a developed view of the tumbler of Figures 16 to 18; and

Figure 20 is a partial perspective of a door illustrating a manner of using the lock of Figures 16 to 19.

The lock of Figures 1 to 8 comprises an outer cylinder 2| adapted to be mounted in a door, a drawer or the like in the usual manner and having a plug or body portion 22 rotatably mounted therein, the plug 22 being formed with an elongated keyhole extending axially thereof. The cylinder 2! is formed with a pair of slots 23 and 24 to receive a tumbler 25 which is slidably mounted in the plug 22 and which is formed with a pair of legs 26 and 21 adapted to straddle the keyhole. The leg 26 as shown in Figure 3 is formed with a plurality of sloping ridges 2B and has a pin 29 secured thereto and lying below the ends of the ridges and the leg 21 is formed with a similar ridge 3! adapted to lie between the ridges 28 on the leg 26. The combined height of the ridges is preferably greater than the space between the legs so that a straight instrument cannot be inserted between the legs at that portion thereof on which the ridges are formed. The tumbler 25 is urged outwardly of the plug 22 by means of springs 32 having caps 33 to engage the end of the tumbler and arranged diametrically opposite to the slots 23 and 26.

A plurality of tumblers 3d are slidably mounted in the plug 22 rearwardly of the tumbler 25 in register with tumblers 35 which are slidably mounted in the cylinder 24 and urged toward the plug 22 by means of springs 36. The springs 36 normally urge the tumblers 35 and tumblers 34 toward the axis of the plug 22, the tumblers 35 at this time preventing relative rotation between the cylinder 2! and plug 22.

A key 3'! is adapted to be used with the lock and as best seen in Figures '7 and 8 is formed with a single cam slot 38 on one side adapted to receive the ridge 3| on leg 21 and with a pair of grooves 39 on its other side to receive the ridges 28 on the leg 26. The end of the key is cut away as indicated at 4| to receive the pin 29 so that the key can slide freely into the keyhole until the pin 29 reaches the end of the cutaway portion 4! and engages the side of the first slot 39. Thereafter further movement of the key into the keyhole will cause the tumb-ler 25 to be cammed downwardly by engagement of the ridges 28 and 3I in the slots 38 and 39, the pin 29 serving merely to engage the first cam slot 39 to move the tumbler 25 downwardly a suiiicient distance tocause the ridges 28 and 3I to engage in the cam slots. The end of the key is formed at one edge with a plurality of cam portions 42 which are of a correct height and space to cause the ends of tumblers 34 to lie flush with the surface of the plug 22 when the key is inserted in the keyhole. If desired, the key may be formed with a longitudinal slot 43 to engage a corresponding projection on the side of the keyhole, thereby to prevent insertion of any except the proper key in the keyhole.

When the key 31 is inserted in the keyhole as indicated in Figure 1, the tumbler 25 will be withdrawn into the plug 22 and the ends of pins 34 will lie flush with the outer surface of said plug. At this time the key may be turned to turn the plug 22 in the sleeve 2|, thereby to operate a suitable locking pawl in any desired manner. The slot 24 is provided in order to permit withdrawal of the key after the plug 22 has been turned, the slot preferably being located in such a position that it will register with the tumbler 25 when the plug 22 has been turned to a position to unlock the lock. With the plug 22 turned to this position the key may be withdrawn, the cam slots and the spring 32 serving at this time to force the tumbler 25 into the slot 24 to permit removal of the key and to prevent accidental turning of the plug 22.

According to another feature of the invention a pair of spring-pressed latch members 44 are provided in the plug 22 adapted to engage notches 45 in the tumbler 25 to hold the tumbler in its position outwardly of the plug 22. These latch members, shown as consisting of two sets of tumblers 41 and 48, preferably extend into the keyhole and are adapted to be cammed outwardly by insertion of the key, thereby to release the tumbler 25 to permit its withdrawal into the plug. This feature increases the difiiculty of withdrawing the tumblers by anything other than the intended key.

Figures 9 to 15 disclose a modified construction, parts therein similar to like parts in Figures 1 to 8, being indicated by the same reference numbers plus 100. In this form there are a pair of bifurcated tumblers I25 and I50 each formed with legs straddling the keyhole. The tumbler I25, as best seen in Figures 14 and 15, is formed with a pair of legs I26 and I21 carrying respectively a pair of ridges I28 and a single ridge I3I. The pin 29 on leg 26 in Figures 1 to 8 is eliminated and the rearward ridge I28 is projected further down to have its end received in the cut-away portion I4I of the key until the key has moved suificiently far into the lock for the edge of the rearmost cam groove I39 to engage the ridge I28. Further movement of the key into the lock thereafter will cam the tumbler I25 downwardly into the cylinder I22 in the same manner as described in connection with Figures 1 to 8.

The rearward tumbler I50 has a pair of legs II and I52, the leg I52 being provided with a single ridge I53 for reception in a cam groove I54 on the same side of the key as the grooves which time the tumbler in the keyhole.

I39. The leg I5I has a pair of ridges I55 adapted to be received in cam grooves I56 on the opposite side of the key as best seen in Figure 10. This leg also carries a pin I51 adapted to engage the key substantially centrally of its height and the key is provided with a longitudinal groove I58 extending from the forward end thereof to the first cam groove 56 to receive this pin. The parts are so proportioned that the pin I51 will engage the side of the first cam groove I56 at the same time that the end of the rearward ridge I28 engages the rearward cam slot I39 so that both tumblers will be withdrawn simultaneously into the cylinder I22 as the key is thrust into the keyhole. The ridges on the tumbler legs in this form preferably overlap in the same manner as in Figures 1 to 8 so that when the front tumbler is withdrawn into the cylinder I22, it is impossible to force a straight instrument through it to engage the tumbler I50 to withdraw it into the cylinder. Thus it is substantially impossible to withdraw the tumblers by any instrument other than the particular key designed for the lock. It will be apparent that by varying the spacing of the ridges on the tumbler legs and by altering the vertical position of the pin I51, a substantially unlimited number of combinations can be obtained.

Figures 16 to 20 illustrate a very simple embodiment of the invention applied to a keyhole lock for preventing insertion of a key into the usual type of keyhole. This construction includes a body portion I60 of a shape to be received in a conventional keyhole as best seen in Figure 18. The body I60 is formed with an eiongated keyhole slot I6I and slidably receives a tumbler I62, which is adapted to project outwardly of the body under the influence of a spring I63. As best seen in Figure 19 the tumbler I62 is formed of a single sheet of metal of I-shape adapted to be folded over at its center andhaving ridges I64 on its opposite legs which ,will lie facing each other in staggered relation when the sheet is folded. One of the legs also carries a pin I65 which will lie in register with the keyhole when the tumbler extends outwardly of the body I60.

A key I66 formed with a plurality of cam grooves I61 on its opposite sides is adapted to be used with the lock, the grooves I 61 being formed to register with the ridges I64. The key also has a longitudinal slot I 68 terminating in a short cam groove I69 to receive the pin I65. When the key is forced into the lock it will slide freely until the pin I65 reaches the cam groove I69, at I62 will be cammed downwardly until the ridges I64 engage in the slots I61. Further movement of the key into the lock will cam the tumbler I62 into the body until the upper end of the tumbler lies flush with the outer surface of the body. At this time the body may be inserted in a conventional keyhole as indicated at I1I in Figure 20, and the key I66 may be withdrawn, thereby allowing the tumbler I62 to move outwardly of the body to lock the body This will prevent insertion of a key, such for example as a skeleton key, in the keyhole and will prevent unauthorized persons from operating the door lock I12.

Preferably a spring-pressed latch member I13 is provided in the body I60 to engage notches I14 in the tumbler, thereby to lock the tumbler in its outward position. When the key is inserted in the lock its end will engage the latch member I13 and force it out of the notches I14, thereby to permit movement of the tumbler. The key may, if desired, be provided with a spring latch I75 adapted to engage a projection H6 on the end of the body Hill so that when the tumbler IE2 is withdrawn, the body [Gil may be pulled out of the keyhole ill by pulling on the key. When it is desired to remove the key and leave the body it! in the keyhole, the operator may hold his finger against the body I69, thereby retaining it in the keyhole as the key is withdrawn.

While several embodiments of the invention have been shown and described, it will be apparent that many changes might be made therein or that various other embodiments might be devised. It is accordingly not intended that the scope of the invention shall be limited to the exact forms shown or otherwise than by the terms of the appended claims.

What is claimed is:

1. A lock comprising a body portion having a keyhole, a bifurcated tumbler slidably mounted in the body portion and having leg portions straddling the keyhole, projections formed on said leg portions, a spring pressed latch engageable with said tumbler to hold it in a position outwardly of the body portion and adapted to be moved out of engagement with the tumbler by a key inserted in the keyhole.

2. A look comprising a body portion formed with a keyhole, a tumbler slidably mounted in said body portion, a pair of projecting ridges on said tumbler both projecting into the keyhole when the tumbler is in a retracted position, the innermost of said ridges extending farther inwardly in a direction parallel to the tumbler axis than the other, and adapted to engage cam slots in a key, said innermost ridge projecting into the keyhole when the tumbler is extended.

3. A look comprising a body portion having a keyhole, a pair of bifurcated tumblers slidably mounted in the body portion each having legs straddling the keyhole, resilient means urging said tumblers outwardly of the body, said legs being formed with overlapping ridges of a combined height substantially equal to the width of the keyhole and normally lying out of. register with the keyhole but in register with the keyhole when the tumblers are withdrawn into the body whereby a straight instrument cannot be inserted in the keyhole.

4. A look comprising a body portion formed with an elongated keyhole, a bifurcated tumbler slidably mounted in the body adjacent the inlet end of the keyhole and having legs straddling the keyhole, said legs being formed with overlapping ridges of a combined height substantially equal to the width of the keyhole and which are in register with the keyhole to prevent insertion thereinto of a straight instrument when the turnbler is withdrawn into the body, resilient means i or urging the tumbler outwardly of the body, and a second tumbler slidable relative to the body into a locked or an unlocked position and remote from the inlet end of the keyhole.

5. A lock comprising a body portion formed with an elongated keyhole, a bifurcated tumbler slidably mounted in the body adjacent the inlet end of the keyhole and having legs straddling the keyhole, said legs being formed with overlapping ridges of a combined height substantially equal to the Width of the keyhole and which are in register with the keyhole to prevent insertion thereinto of a straight instrument when the tumbler is withdrawn into the body, resilient means for urging the tumbler outwardly of the body, and a plurality of tumblers slidable relative to the body into a locked or an unlocked position and remote from the inlet end of the keyhole with 9 their ends in register therewith.

6. A look comprising a body portion formed with a keyhole, a tumbler slidably mounted in said body portion, and ridges on said tumbler extending into the keyhole and of such a height as to block insertion of a straight instrument into the keyhole when the tumbler is in a retracted position.

7. A look comprising a body portion formed with a keyhole, tumbler means slidably mounted in said body portion and including parts lying adjacent each side of the keyhole, and overlapping ridges on said parts of a combined height substantially equal to the width of the keyhole to prevent insertion of a straight instrument into the keyhole.

JALMAR POLKI, 

